Among reactive silicon group-containing organic polymers which are liquid at room temperature, there is one that cures by contacting moisture (hygroscopic moisture) in the air, to thereby produce a rubber-like elastic body, which requires no troublesome tasks such as weighing or mixing base polymers, cross-linking agents, catalysts and the like right before the usage, and there is no chance for an error in blending. Further, since being excellent in adhesiveness, it is widely used as an elastic adhesive and a coating material in the electric and electronic fields, as an architectural sealing material, and the like.
One-component room temperature curable polymer compositions in which amino group-substituted silanes (amino group-containing silane compounds) are blended as components for enhancing adhesiveness are proposed (For instance, refer to Patent Reference 1). The room temperature curable polymer composition is good in field workability since it has low inflammability and small harmful effect, and also its curing speed is not too fast. Further, as components for enhancing adhesiveness, various organic functional silane compounds, other than the amino group-substituted silanes are proposed.
However, in the room temperature curable polymer composition described in Patent Reference 1, although the initial adhesiveness is good, since it is poor in water resistance, specifically, in hot water resistance, the adhesiveness is significantly lowered in water immersion condition. Further, each of the aforesaid room temperature curable polymer compositions in which organic functional silane compounds other than the amino group-substituted silane are blended as the components for enhancing adhesiveness cannot attain a sufficient expression of adhesiveness.
Further, in organic polymers having reactive silicon groups, tackiness tends to be remained on a surface of a cured product, so that the surface of the cured product is contaminated by dirt, earth and sand, dust and the like adhered thereto, resulting that the appearance is apt to be impaired, which is disadvantageous.
In order to reduce such residual tack, conventionally, various studies have been conducted regarding a composition of silicon compounds, a selection of kinds of curing catalysts, air-curing and a blend of dry substance, and the like, and some proposals have been made. For example, there have been proposed a curable composition in which compound having silanol groups and compounds having air oxidation curing unsaturated groups are blended with oxyalkylene polymers having reactive silicon groups, to thereby improve non adhesiveness of dust and the like (stain-proof property) (for instance, refer to Patent Reference 2). Further, there have been proposed a room temperature curable composition in which light-curing substances and unsaturated compounds capable of reacting with oxygen in the air are blended with polyethers each having one or more of (a) reactive silicon group(s) in its molecule, to thereby enhance a contamination prevention effect (for instance, refer to Patent Reference 3). Furthermore, there has been made a proposal to improve the residual tack and further to enhance a weather resistance by blending acrylic compounds (for instance, refer to Patent Reference 4).
However, there has been a problem that during the storage of these curable compositions, a liquid separation and the decrease in adhesiveness are likely to occur. Further, since the curing property is hard to control, there have arisen problems such that not only the sufficient workability cannot be attained, but also fine cracks tend to be made on the surface of the cured product. There are some of the curable compositions which lack sufficient mechanical properties, durability, and the like of the cured products.
In addition, these compositions often require a control of modulus according to the usage, in which the composition with low modulus is needed especially when it is applied to a siding, or to a region where stress relief is required. It is hard to realize the low modulus in the curable compositions in which the residual tack is improved, and further, some of the curable compositions lack the sufficient mechanical properties, durability, and the like of the cured products. Further, the tack often remains on the surface of the cured product of the composition with low modulus. In reality, there have not been obtained curable compositions achieving both the improvement of residual tack and the low modulus.    Patent Reference 1: JP-B2 3343604 (Patent Publication)    Patent Reference 2: JP-A 02-117954 (KOKAI)    Patent Reference 3: JP-A 03-160053 (KOKAI)    Patent Reference 4: JP-A 05-065400 (KOKAI)